Method of manufacturing an organic photodetector

Abstract

A method of manufacturing an organic photodetector is provided. The organic photodetector includes a bulk heterojunction layer 3 between a first electrode 2 and a second electrode 4, wherein the bulk heterojunction layer extends beyond an active photodetector area defined by the overlap area of the first and second electrodes. The second electrode may be a discontinuous electrode defining, with the first electrode, a plurality photodetector elements. In formation of the organic photodetector, the bulk heterojunction layer is heated. Upon heating, a non-polymeric component 3′a of the bulk heterojunction outside the active photodetector areas may migrate into an encapsulation layer 5. The heating may improve resolution of the photodetector.

1 . A method of manufacturing an organic photodetector, wherein the organic photodetector comprises a substrate, a first electrode supported on the substrate, a second electrode, a bulk heterojunction layer comprising an organic electron acceptor and an organic electron donor between the first and second electrodes, and an encapsulation layer comprising an organic material in direct contact with the bulk heterojunction layer wherein:
 the organic photodetector has an active area defined by an overlap area of the first and second electrodes;   the bulk heterojunction layer has an area extending across the active area and outside the active area;   at least one of the organic electron acceptor and the organic electron donor is non-polymeric; and   the method comprises heating the bulk heterojunction layer.   
     
     
         2 . A method according to  claim 1 , wherein:
 the second electrode is a discontinuous electrode comprising a plurality of discrete second electrode areas spaced apart from one another defining, with the first electrode, a plurality of active areas; and   the bulk heterojunction layer is a continuous layer extending across the discrete second electrode areas and between the discrete second electrode areas.   
     
     
         3 . The method according to  claim 1 , wherein the organic electron acceptor is a fullerene or a derivative thereof. 
     
     
         4 . The method according to  claim 4 , wherein the organic electron acceptor is a fullerene derivative of formula (III): 
       
         
           
           
               
               
           
         
         wherein A, together with the C—C group of the fullerene, forms a monocyclic or fused ring group which may be unsubstituted or substituted with one or more substituents. 
       
     
     
         5 . The method according to  claim 5 , wherein the fullerene derivative of formula (III) is selected from formulae (IIIa), (IIIb) and (IIIc): 
       
         
           
           
               
               
           
         
         wherein R 3 -R 15  are each independently H or a substituent. 
       
     
     
         6 . The method according to  claim 1 , wherein the organic electron donor is a polymer. 
     
     
         7 . The method according to according to  claim 6 , wherein the organic electron donor is a conjugated polymer. 
     
     
         8 . The method according to  claim 7 , wherein the polymer comprises a repeat unit of formula (I): 
       
         
           
           
               
               
           
         
         wherein R 1  in each occurrence is independently H or a substituent. 
       
     
     
         9 . The method according to  claim 1 , wherein the first electrode and/or the second electrode comprises at least one layer comprising or consisting of a metal. 
     
     
         10 . The method according to  claim 1 , wherein the distance between any two active areas is less than 10 mm. 
     
     
         11 . The method according to  claim 1 , wherein the bulk heterojunction layer is formed over the first electrode by a coating method. 
     
     
         12 . The method according to  claim 2 , wherein the second electrode is formed by a selective deposition method in each second electrode area. 
     
     
         13 . The method according to  claim 1 , wherein the bulk heterojunction layer heating temperature is in the range of 60-150° C. 
     
     
         14 . The method according to  claim 1  wherein the organic material of the encapsulation is layer is a polymer. 
     
     
         15 . An organic photodetector manufactured according the method of  claim 1 . 
     
     
         16 . An organic photodetector according to  claim 15 , wherein the concentration of at least one of the organic electron donor and the organic electron acceptor in the bulk heterojunction layer is lower in an area outside of an active area than in an active area. 
     
     
         17 . An organic photodetector comprising a substrate, a first electrode supported on the substrate, a second electrode, a bulk heterojunction layer comprising an organic electron acceptor and an organic electron donor between the first and second electrodes and an encapsulation layer comprising an organic material in direct contact with the bulk heterojunction layer, wherein:
 the organic photodetector has an active area defined by an overlap area of the first and second electrodes;   the bulk heterojunction layer extends across the active area and outside of the active area;   at least one of the organic electron acceptor and the organic electron donor is a non-polymeric material; and   the concentration of at least one of the non-polymeric materials in the bulk heterojunction layer is lower in an area outside of the active area than in the active area.   
     
     
         18 . The organic photodetector according to  claim 17 , wherein:
 the second electrode is a discontinuous electrode comprising at least two discrete second electrode areas spaced apart from one another; and   the bulk heterojunction layer is a continuous layer extending across the discrete second electrode areas and between the discrete second electrode areas.   
     
     
         19 . The organic photodetector according to  claim 17  wherein the organic material of the encapsulation layer is a polymer. 
     
     
         20 . A sensor comprising the organic photodetector of  claim 17  and a light source.